JP2000059741A - Coder and decoder for character display image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce data size, while preventing deterioration in quality of a character display image and to simplify the configuration of the decoder at the reproduction side. SOLUTION: A character drawing section 4 draws a character in a bit map (binary) for an oversampled area, and a coding section 5 applies entropy coding to the binary image. A control information generating section 6 transmits an interpolation processing parameter added to a compression code or stores it, so that the decoder 3 converts the scale of the binary image and a multi-valued level image with high image quality for broadcasting through shading.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding device and a decoding device used for transmitting or recording a character display image such as a flash character for a TV broadcast or the like.

[Summary of the Invention] The present invention relates to image compression encoding / decoding when transmitting and recording a character display image such as a bulletin super character of a TV broadcast.
A binary image in which characters are drawn in a bitmap (binary) in the oversampled area is compression-encoded, and the decoding apparatus performs scale conversion and shading of the binary image to provide a high-quality multilevel level for broadcasting or the like. In order to convert the image into an image, an interpolation processing parameter is added to the compression code and transmitted or stored.

That is, the present invention provides a method of generating, compressing, transmitting and recording a breaking character super image by a new method. While reducing the data size to be transmitted to each station, the structure of the "TV bulletin super character drawing transmission terminal" at each station can be simplified and its function can be generalized, and the image content can be transferred to the central office (located in Tokyo). It is not necessary to change or modify the "TV bulletin super character drawing transmission terminal" of the local station on the playback side even if the
By making almost all of the various data to be prepared in the bulletin super character drawing transmission terminal "unnecessary, the management and maintenance of the entire system is facilitated, and it is possible to flexibly respond to sudden changes in the drawing contents.

[0004]

2. Description of the Related Art As a specific example of a system for carrying out breaking news of TV broadcasts using a text super, etc., as a result of a national election report, the names of winners and winners will be broadcast simultaneously and synchronously by broadcasting stations nationwide. A system for performing superposition will be described.

[0005] On the day of the election, the host computer of the central bureau in Tokyo, with the progress of the counting of votes, sends information on the candidates who are determined to be winning or winning at that time (whether the winning or winning is determined,
Candidate names, political parties, constituencies, etc.) to a number of local stations across the country via a communications network. A drawing device provided at each station (this device provided at each station is referred to as a "TV bulletin super character drawing sending terminal") receives this information, draws and generates a character super image for broadcasting, and generates a local TV from each station. We will carry out this character supervision in broadcasting.

In this conventional system, information transmitted from the Tokyo side to each local station is only text information, and the super image is drawn by a drawing program built in the "TV bulletin super character drawing transmission terminal" of each station. It is broadcasted using fonts. Similarly, a system that provides a nationwide emergency supervision of emergency disaster information such as earthquakes and tsunamis can also use characters such as earthquake and tsunami information obtained from the Japan Meteorological Agency online (e.g. Information is transmitted to local stations nationwide, and broadcasts nationwide in a similar manner. Hereinafter, this method will be referred to as a “flash report method by transmitting character information”.

[0007] In the above-mentioned "flash report system by transmitting character information", an image processing unit for controlling (1) control of image transmission and image generation is provided in a "TV flash report super character image transmission terminal" provided in each local station. (2) It is common to incorporate a drawing data group of image parts such as character fonts, base images and logos.

[0008] The drawing processing section shown in (1) controls data reception and transmission with a communication line, analyzes received data, generates a drawing of a character image for broadcasting, and sends the form (scroll / scroll).
Special effects such as wipe / shape change) are controlled.

[0009]

However, in the above-mentioned conventional "TV bulletin super character drawing transmission terminal", when the content or layout of the broadcast image is changed, (2)
In addition to the necessity of replacing the drawing data group shown in (1), it is often necessary to modify or add the drawing processing unit shown in (1). Further, the content change of the broadcast image needs to be carried out simultaneously by a large number of "TV bulletin super character drawing transmission terminals" of each station in the whole country. For example, in a national election bulletin, in the short term between the announcement date and the election date,
Designed a screen design for the Election Bulletin Super, and launched the "TV"
It is necessary to repair the Bulletin Super Character Drawing Transmission Terminal at the same time and conduct a nationwide test to confirm its function.

[0010] As described above, the cost and labor involved in a series of preparation work for repairing / preliminary test / simultaneous switching of the “TV bulletin super character drawing transmission terminal” nationwide due to the change of the image content are extremely large. Furthermore, it is extremely difficult to deal with all stations in a case where a change in screen content or the like is required immediately before or during operation.

[0011] Therefore, from the viewpoint of transmitting nationwide simultaneous super images, a method of transmitting image data itself from Tokyo to stations nationwide is conceivable.

If this system can be put to practical use, the "T
In addition to simplifying the drawing processing unit of (1) in the "V Bulletin Super Character Drawing Transmission Terminal", changing the "TV Bulletin Super Character Drawing Transmission Terminal" of the local station even if the image content is changed on the transmission side. In addition, the various types of data described in (2) to be prepared in the “TV bulletin super character drawing transmission terminal” are almost unnecessary, and the management and maintenance of the entire system are facilitated, and the drawing contents are reduced. Can respond flexibly to sudden changes.

However, the use of the above-described image transmission method has the following problems and cannot be put to practical use.

For example, in the case of a super image plate having a horizontal size of about 600 pixels horizontally and about 60 lines vertically and dubbed on the bottom of a TV screen, each color of color has 8 bits / pixel and RGB.
・ It becomes 108KB in B. Compared to the original character information, which requires only about 1 to 2 KB at most, the image size itself is not practically suitable in terms of transmission cost and transmission time. Therefore, the commonly used JP
Approximately 1/50 to 1/100 to reduce the transmission size to about the original character data size by image compression encoding such as EG
If image compression is performed at a high compression ratio of 100, the image quality deteriorates significantly and cannot be used for image quality for broadcasting.

In particular, in the case of a character image, the pixel level changes sharply at the boundary between the background and the character pattern. Therefore, "a high level correlation between adjacent pixels" is a prerequisite for an energy compression type image compression method such as JPEG. There are parts that do not conform to the assumption that the image quality is degraded at the time of high compression. In a character image, for example, a background image and a character image are compared with a normal natural image image in which a high value of the adjacent pixel correlation (correlation coefficient p> 0.9) is almost uniformly satisfied over the entire image. There are many parts such as boundaries where the pixel level changes rapidly and the value of the correlation coefficient p is almost zero. This property is the reason that it is more difficult to apply a normal energy compression type image encoding method such as JPEG to a character image than to a general natural image.

For this reason, in order to make the image quality degradation less noticeable, the compression ratio in these image compression methods must be reduced, and as a result, the amount of transmission codes increases. According to the experiment, the results shown in the following Table 1 were obtained.
Conventional compression schemes are not suitable for this purpose. Table 1 shows a case in which a TV bulletin super image used for “displaying the name of a winning candidate” in an election report is compressed by JPEG.

[Table 1]

The present invention has been made in view of the above circumstances, and it is possible to reduce the data size of a character display image while preventing the quality of the character display image from deteriorating, and to simplify the configuration of a decoding device on the reproduction side. It is a main object to provide an encoding device and a decoding device.

[0018]

According to one aspect of the present invention, there is provided an encoding apparatus used in transmitting or recording a character display image, comprising: Character drawing means for generating a binary image in which characters are drawn with a bit map, compression encoding means for entropy encoding the generated binary image, and a decoding device side for compressing the image compressed by the compression encoding means Control information generating means for generating control information for converting into a multi-valued image, and integrating means for generating and transmitting or recording integrated data obtained by adding the generated control information to the compressed image. It is characterized by:

According to a second aspect of the present invention, in the character display image encoding apparatus according to the first aspect, the control information is DD as a parameter for performing DD conversion (digital sampling rate conversion) on the decoding apparatus side. Parameters for specifying a conversion algorithm, conversion parameters to be given to the DD conversion algorithm, and parameters for rendering the broadcast character image on the decoding device side include coloration information, presence / absence of shadowing and shadow shift amount information, and outline. It is characterized by including at least one of the presence / absence and its width information, and the drawing movement effect information.

According to a third aspect of the present invention, there is provided an apparatus for reproducing a character display image encoded by the encoding apparatus according to the first aspect, wherein the entropy-encoded binary image is decoded. Means for converting a decoded binary image into a converted image based on the control information according to claim 2 to generate a resolution-converted image; Image generating means for converting the image whose resolution has been converted into a color image based on the control information.

According to a fourth aspect of the present invention, in the character display image decoding apparatus according to the third aspect, the three primary colors R, G, and B are used as coloring information in the control information transmitted from the encoding apparatus. The image generation means includes a numerical value, and generates a color image by generating a color separation image of R, G, and B primary colors based on the constant values of the three primary colors.

According to a fifth aspect of the present invention, in the character display image decoding apparatus according to the third aspect, based on presence / absence of shadowing and shadow shift amount information in control information transmitted from the encoding apparatus side. The image generating means generates images having different pixel level distributions, shifts the position of the entire image by a specified amount, and generates an image with a shadow by overwriting the original image. .

According to a sixth aspect of the present invention, in the character display image encoding apparatus according to the first or second aspect, the integration means includes means for converting the compression-encoded binary image and the control information added thereto into a binary image. It has a function of generating and transmitting or storing integrated data with an index number, and a function of transmitting the integrated data in response to a request for transmitting integrated data with a specified index number from the decoding device side. It is characterized by:

According to a seventh aspect of the present invention, there is provided an apparatus for reproducing a character display image encoded by the character display image encoding apparatus according to the sixth aspect, wherein an index number is designated for the encoding apparatus. And a function of receiving the integrated data transmitted from the encoding device in response to the transmission request.

The invention according to claim 8 is the invention according to claims 3, 4, 5, and 7.
In the character display image decoding device according to any one of the above, provided with a storage unit that adds an index number to the compression-encoded image generated by the encoding device and the control information added thereto and accumulates, When an image corresponding to the index number designated by the encoding device is stored in the storage means, the image is decoded.

According to a ninth aspect of the present invention, there is provided a character display image decoding apparatus having a function of transmitting an index number designating an image stored in the character display image decoding apparatus.

According to the above configuration, as compared with an image compression method such as JPEG or the like, it is possible to perform high-rate compression without deteriorating image quality due to compression encoding of a character display image, and reduce the amount of information required for transmission and recording. Thus, transmission and recording costs can be reduced.

The decoding device only decodes the broadcast data as an image, does not know the layout or image expression of the flash super image at all, and is equipped with a character font and high-quality character drawing means. There is no need, and the configuration is simplified. Further, the generalization of the reproduction function eliminates restrictions on character drawing, expands the degree of freedom of expression, facilitates management and maintenance of the entire system, and can flexibly respond to sudden changes in drawing contents.

[0029]

FIG. 1 is a block diagram showing a character image transmission / recording system which is an embodiment of a character display image encoding apparatus and decoding apparatus according to the present invention.

The character image transmission / recording system 1 includes an encoding device 2 and a decoding device 3. The encoding device compresses and encodes a character display image, and a high-resolution image on a reproduction side. Is generated and transmitted to the decoding device 3 side, and the decoding device 3 decodes the character display image based on the control information to generate T
Generate a V color image.

The encoding device 2 has a character drawing unit 4 for drawing characters on the oversampled domain of the binary bitmap.
An encoding unit 5 that compresses the binary image by lossless information amount by entropy encoding to generate a code code1, a control information generation unit 6 that generates codes code2 and code3 described later as control information, and an encoding unit 5 Code generated by
1. code2 and co generated by the control information generator 6
An integration unit 7 that generates a code codeA obtained by integrating the de3 and transmits the codeA to the decoding device 3 is provided.

In this case, the character drawing unit 4 sets the oversample domain (Height, Width) =
On the (M, N), the following character drawing parameters P1, P2,
A character is drawn by appropriately selecting P3 or the like to obtain a binary image.

Parameter P1: character size, parameter P2: type of font Parameter P3: style (bold, italic, space between characters, etc.) These drawing parameters P1, P2, and P3 are referred to as "character drawing parameters for encoding". Name.

Here, the "oversampled domain" is a two-dimensional array of a spatial area ((Height, Width) = (M, N) larger than the character display frame actually broadcasted. A pixel is a binary bitmap domain.

Various algorithms, such as Huffman code, Lampel & Ziv code, and arithmetic code, exist in the entropy coding executed by the coding unit 5, so that an appropriate implementation time is taken into consideration in consideration of calculation time / coding efficiency. You just have to choose one.

The control information generating section 6 generates control information for converting the oversampled domain of the binary bitmap into a multi-value gray image by DD conversion (described later) as code code2. The control information constituting the code code 2 is D
A parameter that specifies the D conversion algorithm and its DD
It is composed of two types of conversion parameters given to the conversion algorithm. The parameter that specifies the DD conversion algorithm is, for example, discrimination information such as a combination of a two-dimensional LPF and a two-dimensional subsample, bilinear interpolation, bicubic interpolation, and spline interpolation. The conversion parameter given to the DD conversion algorithm may be, for example, only the size parameter (Height, Width) = (m, n) of the multi-valued gray image in the case of bilinear interpolation. In this case, m / M in the height direction and n / N in the horizontal direction
To produce an interpolated image with a compression ratio of

Further, the control information generating section 6
Coding the control information for controlling the drawing of the broadcast character image on the side co
Generate as de3. The control information of this code code3 includes:
As character drawing parameters for converting a multi-valued gray image into a color image to be actually broadcast, parameter P4: coloring parameter P5: presence or absence of shadow and shift amount of shadow Parameter P6: existence of outline and its width Parameter P7 : There is information such as drawing movement effects (moving effects such as opening the character display image and horizontal scrolling). These parameters are referred to as “terminal-side character drawing parameters”.

On the other hand, the decoding device 3
A: a decomposing unit 8 for separating codes code1, code2, and code3 from A; a decoding unit 9 for decoding a binary bitmap oversample domain based on the separated code1; co
a gray image generation unit 10 for performing DD conversion to a multi-value gray image based on de2, and a code code
And a TV image generation unit 11 that converts the image into a color TV image based on the C.3.

<Operation of Embodiment><< Operation of Encoding Device 2 >> Next, the operation of this embodiment will be systematically described.

In the character drawing section 4, a space area ((Height, Width) = larger than the character display frame actually broadcasted)
(M, N) two-dimensional array, unit is number of pixels, 1 pixel is binary)
Is created for each of a plurality of partial character strings on the binary bitmap domain (oversampled domain). At this time,
The character pattern to be drawn is binary.

In this embodiment, a character super image to be modeled is divided into several types of character blocks, and characters are rendered by changing the following character rendering parameters for each of the character blocks. .

Character size, font type, style (bold, italic, character spacing, etc.), coloring,
The presence / absence of the shadow is represented by the amount of shift of the shadow, the presence / absence of the outline and its width, a drawing movement effect (moving effect such as opening a character display image and horizontal scrolling).

In the bulletin supervision of names of elected / winning candidates in the election, the character blocks are, for example, whether they are elected / winning, names of candidates, names of factions, names of new / current / formal candidates, names of constituencies, etc. and so on.

The encoding unit 5 executes lossless information compression by entropy encoding of a binary bitmap oversampled domain.

In transmission of a character display image over a network, a reduction in the amount of transmitted information is strongly required. On the other hand, since the display is a character display for broadcasting, image quality deterioration due to compression of the information amount must be avoided as much as possible.

Most of the character image drawn on the binary bitmap oversample domain is a background value (this is symbol “0”) and a character value (this is symbol “1”). Appears less frequently. As a result,
Since the occurrence probability of “1” takes a very small value as compared with the occurrence probability of “0”, if a so-called “lossless compression by entropy coding” is applied, which assigns a short code in accordance with the occurrence probability of a symbol, the image quality is reduced. Without deteriorating at all,
The amount of code can be significantly reduced.

In the control information generation unit 6, as described above, D
A code code2 is generated as control information for D conversion, and
Code code3 is generated as a character parameter on the terminal side. Then, the integrating unit 7 generates the code code1 generated by the encoding unit 5 and the code code1 generated by the control information generation unit 6.
2 and code3 are integrated to generate a code codeA, which is transmitted to the decoding device 3.

<< Operation of Decoding Device 3 >> In the decoding device 3, first, the decomposing unit 8 separates the codes code1, code2 and code3 from the received code codeA. Decoding unit 9
Then, the binary bitmap oversample domain is decoded based on the separated code1.

Normally, in general character drawing on a personal computer or the like, it is common to draw character fonts in binary on a screen. Therefore, when converted to an interlaced scanning TV signal with a narrow frequency band as it is, Flicker and diagonal jaggedness occur. Therefore, the following processing is performed,
An improvement in character quality on a TV screen is realized.

That is, the gray image generating unit 10 converts the binary character pattern image created on the oversampled domain into an image having a smaller space size (appropriate resolution conversion means indicated by the separated code code2). (He
ight, Width) = (m, n). This area is referred to as a “multi-value gray image”.

The resolution conversion is as follows: horizontal: M → m, vertical:
This is a two-dimensional digital sampling rate reduction conversion (DD conversion) of N → n. That is, an oversampled domain consisting of (M, N) binary sample points is converted to a multivalued gray image consisting of a smaller number of sample points (m, n) and in which a character drawing portion is shaded. Convert.

The pixel value of each coordinate (i, j) of the multi-valued gray image (this is referred to as “interpolated value”) is represented by coordinates (i * M / m) on the oversampled domain corresponding to the coordinates (i, j). , j * N /
Sample point group (binary) in an appropriate neighboring area centered on n)
Is calculated by the sum of the weighting factors of For this reason, the interpolation value of the coordinate point (i, j) is generally multi-valued. Since the coordinates (i * M / m, j * N / n) on the oversampled domain are not always integers, the sample points (i, j) of the multi-valued gray image
Sample value (binary) on the oversample domain corresponding to
Is not always present, but if it does not exist, it is generally considered to take "0".

As the DD conversion, a combination of a two-dimensional LPF and a two-dimensional subsample, a bi-linear interpolation
olation), bi-culbic interpolation,
An appropriate one may be selected from various existing resolution conversion means such as spline interpolation in consideration of calculation time and image quality. This selection depends on the encoding device 2
This is performed by the control information generation unit 6 on the side, and in the form of code code2,
This is transmitted to the decoding device 3.

It should be noted here that when the above-mentioned binary bitmap oversampled domain is subjected to DD conversion to a multi-valued gray image, shading (multi-value conversion) of binary expression and resizing (horizontal of character font) are performed. (Vertical size scaling) and the like are processed simultaneously. In particular, shading of drawing characters is an essential process for realizing high quality character quality for broadcasting.

Next, the TV image generation unit 11 converts the generated multi-valued gray image into a color TV based on the code code3.
Convert to image. That is, character drawing parameters P4 to P7 of code code3, such as coloring information, information on the presence / absence of shadows and the amount of shift of shadows, information on the presence / absence of outlines and their widths, and drawing movement effects (wipe opening of character display images, A color image for actually broadcasting a multi-value gray image is generated based on effect information such as a moving image effect such as horizontal scrolling.

For example, when the coloring information of the character drawing parameter P4 is a constant value of the R, G, B three primary colors, the multi-value gray image is multiplied by the constant value of the R, G, B three primary colors to obtain three colors. A separated image is generated, and this is combined to generate a TV color image. Further, for example, in the case of information on the presence / absence of shadow and the amount of shift of the shadow in the character drawing parameter P5, a multilevel gray image is multiplied by a certain constant to generate an image in which the entire level is lowered, and the drawing is performed. A shadowed image is generated by a method of overwriting the original multi-valued gray image on a position shifted by a specified amount. The generated TV image is transmitted as a TV flash super screen.

<Modification 1><< Modification 1 >> In the above-described embodiment, the encoding unit 5 generates the code code1 by compressing the binary image by the amount of lossless information by entropy encoding. However, when a plurality of entropy encoding algorithms can be provided on the receiving side, information specifying the algorithm selected by the encoding unit 5 and parameters for decoding may be included as the code code1. For example, when a static Huffman code is selected, if the decoding unit 9 prepares a plurality of codebooks, the codebook selection information is included in this parameter. When an adaptive coding such as an adaptive Huffman code or an adaptive arithmetic code is selected, “order” is included in this parameter. In this case, since the character drawing parameters P1, P2, and P3 at the time of the encoding are processing of the encoding unit 5 only,
It is not always necessary to include it in the code code1 transmitted to the side.

<Modification 2: Code Generation in Character Blocks in Encoding Apparatus 2> When dividing a flash super image into a plurality of blocks, for example, on the election flash screen, it is determined whether winning / winning, candidate name, affiliation, etc. When divided into four character blocks of a political party and a constituency, the character drawing parameters P1, P2, and P3 at the time of encoding may be generally set to different values for each block. The quality can be finely controlled. In this case, even if a plurality of character blocks are drawn all at once on one binary bitmap oversample domain, and entropy-encoded as a single binary bitmap to generate a single code code1 Good.

On the other hand, entropy code compression may be performed for each individual character block, and a plurality of codes obtained may be collectively referred to as code code1.

Similarly, when the binary bitmap oversampled domain is converted into a multi-valued gray image by the DD conversion, the interpolation method and the interpolation parameters are changed to achieve the optimum character image quality for each block. It may be different for each character block on the oversampled domain, and these may be collectively referred to as code code2.

Further, it is conceivable to change the character drawing parameters P4, P5, P6, P7 on the terminal side of the code code3 for each character block.

<Modification 3: Transmission of Base Image> In the election bulletin screen, characters are often drawn on a color base image instead of just superimposing the characters on the TV screen. For this reason, the base image may be previously mounted in the “TV breaking super character drawing sending terminal”, that is, the decoding device 3. However, due to versatility and expandability, when the whole breaking system starts up, This base image may be distributed to each receiving terminal via a communication network. Since this transfer is basically performed only once, there is no practical problem even if the transmission size of the base image is large.

<Modification 4: Message Transmission Method via Network, Corresponding to Claims 6 and 7> When distributing a plurality of flash messages via a network, a unique sequence number is used for a series of messages (the integrated data). Index number)
, The decoding device 3 detects the missing sequence number (index number) and automatically issues a request for retransmission of the missing message, thereby increasing the reliability of data transmission. . In this case, the transmitted message is accumulated on the integration unit 7 of the encoding device 2, and the integrated data as the missing message is stored in response to a retransmission request specifying the sequence number (index number) from the decoding device 3. Send. The transmission message sequence number management mechanism is effective, for example, for improving the reliability of the communication without impairing the characteristics of the multicast / IP communication protocol having a small amount of traffic and an excellent promptness.

<Modification 5: Transmission of Index Number of Character Image Stored in Decoding Apparatus 3, Corresponding to Claims 8 and 9>"TV breaking super character drawing transmission terminal" of each station, ie, decoding apparatus 3 From the encoding device 1 to the code co
Instead of transmitting deA each time, a plurality of character image data is stored in the decoding device 3 in advance, and the encoding device 2 transmits only the index numbers of the necessary image data, thereby enabling the character bulletin super. Speeding up and reducing network traffic can be achieved. It should be noted that the preparation of the advance data is performed in a preparation stage of the device 3. Specifically, most of the coded data codeA of the image for which the character bulletin super is expected is distributed in advance on a large-capacity medium such as a CD-ROM, and is installed in the decoding device 3 of each station in advance. Alternatively, transmission may be performed in the form of the code code A in anticipation of an idling period in which the present system does not transmit a flash super character image. Further, when the image index number is received but the image does not exist on the device 3 during the production operation of the breaking character super, the encoding device is regarded as a loss as in the above-described processing, and The process of making a retransmission request of the code codeA to the two sides can be used.

As to the method of generating the index number transmitted from the encoding device 2, there is a method of defining a unique index number from the content of the flash character.
In other words, for example, in the election bulletin, each item of election / winning, election district name and candidate name is quantified in advance (representing election / winning is represented by 0 or 1, election district code, A candidate code in a constituency is defined in advance, and an index number is generated from such numerical information. By using this method, a unique index number is uniquely determined according to the content of the breaking character,
Both the encoding device 2 and the decoding device 3 can independently generate index numbers and identify and recognize them. In the preparation stage of preparing the above preliminary data, since the transmission order of the breaking character message sent by the actual breaking super is not known,
This index number generation method is effective. The generation and assignment of the index number may be used in combination with the above-described method in which the encoding device 2 assigns a sequence number to a series of messages in the order of transmission.

[0066]

As described above, according to the present invention, for example, when transmitting and recording a character display image such as a bulletin super character of a TV broadcast, two characters are added to the oversampled domain before the generation of the character display image. Compression encoding of a binary image in which a character is drawn with a value bitmap, and an interpolation parameter for converting the binary image into a high-quality multi-valued gray image for broadcasting or the like by scale conversion and shading. To be transmitted or recorded.

For this reason, compared with image compression methods such as JPEG, high-rate compression is possible without image quality deterioration accompanying compression encoding of character display images, the amount of information required for transmission and recording can be reduced, and transmission and recording can be reduced. The cost of recording can be reduced. In addition, the reproducing side may simply decode the broadcast data as an image, as compared with a method in which character information is transmitted and the bulletin super is rendered as a character on the reproducing side. That is, the reproducing side does not need to be concerned with the layout and image expression of the flash super image at all. As a result, the configuration on the reproduction side is simplified, for example, there is no need to provide a character font or a high-quality character drawing means, so that the production and operation costs can be reduced. Further, the generalization of the reproduction function can eliminate the restriction on the character drawing and expand the freedom of expression. In this way, management and maintenance of the entire system is facilitated, and it is possible to flexibly respond to sudden changes in the drawing contents.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a character image transmission / recording system which is an embodiment of a character display image encoding device and a decoding device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Character image transmission / recording system 2 Encoding device 3 Decoding device 4 Character drawing unit 5 Encoding unit 6 Control information generation unit 7 Integration unit 8 Decomposition unit 9 Decoding unit 10 Gray image generation unit 11 TV image generation unit

Claims (9)

[Claims] 1. An encoding device used when transmitting or recording a character display image, comprising: a character drawing means for generating a binary image in which characters are drawn with a binary bitmap in an oversampled domain; Compression encoding means for entropy encoding the binary image, and control information generating means for generating control information for converting the image compressed by the compression encoding means into a multi-valued image on the decoding device side; A character display image encoding device, comprising: integrated means for generating integrated data in which the generated control information is added to the compressed image and transmitting or recording the integrated data. 2. The character display image encoding device according to claim 1, wherein the control information specifies a DD conversion algorithm as a parameter for performing a DD conversion (digital sampling rate conversion) on the decoding device side. Parameters, including conversion parameters to be given to the DD conversion algorithm, as parameters for rendering the broadcast character image on the decoding device side, such as coloring information, shadowing presence / absence information and shadow shift amount information, outline presence / absence and its width A character display image encoding device, comprising: at least one of information and drawing effect information. 3. An apparatus for reproducing a character display image encoded by the encoding apparatus according to claim 1, wherein: a decoding unit that decodes the entropy-encoded binary image; A resolution conversion unit that performs DD conversion on the decoded binary image based on the control information described in item 2 to generate an image whose resolution is converted, based on the control information described in claim 2. A character display image decoding apparatus, comprising: an image generation unit that converts the image whose resolution has been converted into a color image. 4. The character display image decoding device according to claim 3, wherein the coloring information in the control information transmitted from the encoding device includes constant values of R, G, and B primary colors. A character display image decoding apparatus, characterized in that the image generation means generates a color image by generating a color separation image of R, G, and B primary colors based on the constant values of the three primary colors. 5. The apparatus for decoding a character display image according to claim 3, wherein the image generation means is based on presence / absence of shadowing and shadow shift amount information in control information transmitted from the encoding apparatus side. Generates images with different pixel level distributions,
A character display image decoding apparatus, characterized in that, after shifting the position of the entire image by a specified amount, a shadowed image is generated by overwriting the original image. 6. The character display image encoding device according to claim 1, wherein the integrating means assigns an index number to the compressed and encoded binary image and the control information assigned to the binary image. A function of generating and transmitting or storing integrated data, and a function of transmitting the integrated data in response to a request for transmitting integrated data of a designated index number from the decoding device side. Encoding device for character display images. 7. A device for reproducing a character display image encoded by the character display image encoding device according to claim 6, wherein an index number is designated for the encoding device and the integrated data A character display image decoding device, comprising: a function of requesting transmission and a function of receiving integrated data transmitted from an encoding device in response to the transmission request. 8. A decoding apparatus for character display images according to claim 3, wherein the compression-encoded image generated by the encoding apparatus and the control information added thereto. Storage means for adding an index number to the image data, and when an image corresponding to the index number specified by the encoding device is stored in the storage means, the image is decoded. Device for decoding character display images. 9. A character display image encoding device having a function of transmitting an index number designating an image stored in the character display image decoding device according to claim 8.